Certain features of integrated waveguide circuitry call for the dumping or absorption of light in a controlled manner. Light may need to be confined so it does not escape into the waveguide substrate and is not back reflected into the waveguide from which it came.
Low reflection terminations for waveguides based on anti-reflection (AR) coated angled facets exist and are successful at reducing back reflections into a waveguide. They are not suitable, however, for beam-dumping because light is released into the substrate rather than being absorbed.